New York Codes, Rules and Regulations
Title 12 - DEPARTMENT OF LABOR
Appendices
Appendix A-1

Current through Register Vol. 45, No. 52, December 27, 2023

Note: Explanatory of Subparts 14-11 and 14-12 and containing matter which is not mandatory unless specially referred to in the sections therein.

SECTION 1

EFFICIENCY OF JOINTS

A-1 Efficiency of riveted joints. The ratio which the strength of a unit length of a riveted joint has to the same unit length of the solid plate is known as the efficiency of the joint and shall be calculated by the general method illustrated in the following examples:

TS = tensile strength stamped on plate, pounds per square inch.

t = thickness of plate, inches.

b = thickness of buttstrap, inches.

P = pitch of rivets, inches, on row having greatest pitch.

d = diameter of rivet after driving, inches, = diameter of rivet hole.

a = cross-sectional area of rivet after driving, square inches.

s = shearing strength of rivet in single shear, pounds per square inch, as given in section 14-11.20.

S = shearing strength of rivet in double shear, pounds per square inch, as given in section 14-11.20.

c = crushing strength of mild steel, pounds per square inch, as given in section 14-11.19.

n = number of rivets in single shear in a unit length of joint.

N = number of rivets in double shear in a unit length of joint.

A-2 Example: lap joint, longitudinal or circumferential, single-riveted.

A = strength of solid plate = P × t × TS.

B = strength of plate between rivet holes = (P - d)t × TS.

C = shearing strength of one rivet in single shear = n × s × a.

D = crushing strength of plate in front of one rivet = d × t × c.

Divide B, C, or D (whichever is the least) by A, and the quotient will be the efficiency of a single-riveted lap joint as shown in Figure A-1.

TS = 55,000 psi

t = 1/4 in. = 0.25 in.

P = 15/8in. = 1.625 in.

d = 11/16 in. = 0.6875 in.

a = 0.3712 sq. in.

s = 44,000 psi

c = 95,000 psi

A = 1.625 × 0.25 × 55,000 = 22,343

B = (1.625 - 0.6875)0.25 × 55,000 = 12,890 .......

C = 1 × 44,000 × 0.3712 = 16,332

D = 0.6875 × 0.25 × 95,000 = 16,328

12,890(B) = 0.576 = efficiency of joint 22,343(A) .......

Click to view image

Note: Reference herein to specifications SA (ferrous) or SB (nonferrous) shall be understood to mean SA or SB specifications as published by the A.S.M.E. with latest addenda.

A-3 Example: lap joint, longitudinal or circumferential, double-riveted.

A = strength of solid plate = P × t × TS.

B = strength of plate between rivet holes = (P - d)t × TS.

C = shearing strength of two rivets in single shear = n × s × a.

D = crushing strength of plate in front of two rivets = n × d × t × c.

Divide B, C, or D (whichever is the least) by A, and the quotient will be the efficiency of a double-riveted lap joint, as shown in Figure A-2.

TS = 55,000 psi

t = 5/16 in. = 0.3125 in.

P = 2 7/8 in. = 2.875 in.

d = 3/4 in. = 0.75 in.

a = 0.4418 sq. in.

s = 44,000 psi

c = 95,000 psi

A = 2.875 × 0.3125 × 55,000 = 49,414

B = (2.875-0.75)0.3125 × 55,000 = 36,523 .......

C = 2 × 44,000 × 0.4418 = 38,878

D = 2 × 0.75 × 0.3125 × 95,000 = 44,531 .......

36,523(B) = 0.739 = efficiency of joint. 49,414(A) .......

Click to view image

A-4 Example: butt- and double-strap joint, double-riveted.

A = strength of solid plate = P × t × TS.

B = strength of plate between rivet holes in the outer row = (P - d)t × TS

C = shearing strength of two rivets in double shear, plus the shearing strength of one rivet in single shear = N × S × a + n × s × a.

D = strength of plate between rivet holes in the second row, plus the shearing strength of one rivet in single shear in the outer row = (P - 2d)t × TS + n × s × a.

E = strength of plate between rivet holes in the second row, plus the crushing strength of buttstrap in front of one rivet in the outer row = (P - 2d)t × TS + d × b × c.

F = crushing strength of plate in front of two rivets, plus the crushing strength of buttstrap in front of one rivet = N × d × t × c + n × d × b × c.

G = crushing strength of plate in front of two rivets, plus the shearing strength of one rivet in single shear = N × d × t × c + n × s × a.

H = strength of buttstraps between rivet holes in the inner row = (P - 2d) 2b × TS.

This method of failure is not possible for thicknesses of buttstraps required by these rules and the computation need only be made for old boilers in which thin buttstraps have been used. For this reason this method of failure will not be considered in other joints.

Divide B, C, D, E, F, G, or H (whichever is the least) by A, and the quotient will be the efficiency of a butt- and double-strap joint, double-riveted, as shown in Figure A-3.

TS = 55,000 psi

t = 3/8 in. = 0.375 in.

b = 5/16 in. = 0.3125 in.

P = 4 7/8in. = 4.875 in.

d = 7/8 in. = 0.875 in.

a = 0.6013 sq in.

s = 44,000 psi

S = 88,000 psi

c = 95,000 psi

Number of rivets in single shear in a unit length of joint = 1. Number of rivets in double shear in a unit length of joint = 2. .......

A = 4.875 × 0.375 × 55,000 = 100,547

B = (4.875 0.875) 0.375 × 55,000 = 82,500

C = 2 × 88,000 × 0.6013 + 1 × 44,000 × 0.6013 = 132,286

D = (4.875 - 2 × 0.875) 0.375 × 55,000 + 1 × 44,000 × 0.6013 = 90,910

E = (4.875 - 2 × 0.875) 0.375 × 55,000 + 0.875 × 0.3125 × 95,000 = 90,429

F = 2 × 0.875 × 0.375 × 95,000 + 1 × 0.875 × 0.3125 × 95,000 = 88,320

G = 2 × 0.875 × 0.375 × 95,000 + 1 × 44,000 × 0.6013 = 88,800

82,500(B) = 0.820 = efficiency of joint. 100,547(A) .......

Click to view image

A-5 Example: butt- and double-strap joint, triple-riveted.

A = strength of solid plate = P × t × TS.

B = strength of plate between rivet holes in the outer row = (P - d) t × TS.

C = shearing strength of four rivets in double shear, plus the shearing strength of one rivet in single shear = N × s × a + n × s × a.

D = strength of plate between rivet holes in the second row, plus the shearing strength of one rivet in single shear in the outer row = (P - 2d) t × TS + a × s × a.

E = strength of plate between rivet holes in the second row, plus the crushing strength of buttstrap in front of one rivet in the outer row = (P - 2d) t × TS + d × b × c.

F = crushing strength of plate in front of four rivets, plus the crushing strength of buttstrap in front of one rivet = N × a × t × c + n × d × b × c.

G = crushing strength of plate in front of four rivets, plus the shearing strength of one rivet in single shear = N × d × t × c + a × s × a.

Divide B, C, D, E, F, or G (whichever is the least) by A, and quotient will be the efficiency of a butt- and double-strap joint, triple-riveted, as shown in Figure A-4.

TS = 55,000 psi

t = 3/8 in. = 0.375 in.

b = 5/16 in. = 0.3125 in.

P = 6 1/2 in. = 6.5 in.

d = 13/16 in. = 0.8125 in.

a = 0.5185 sq. in.

s = 44,000 psi

S = 88,000 psi

c = 95,000 psi

Number of rivets in single shear in a unit length of joint = 1. Number of rivets in double shear in a unit length of joint = 4. .......

A = 6.5 × 0.375 × 55,000 = 134,062

B = (6.5 - 0.8125) 0.375 × 55,000 = 117,304

C = 4 × 88,000 × 0.5185 + 1 × 44,000 × 0.5185 = 205,326

D = (6.5 - 2 × 0.8125) 0.375 × 55,000 + 1 × 44,000 × 0.5185 = 123,360

E = (6.5 - 2 × 0.8125) 0.375 × 55,000 + 0.8125 × 0.3125 × 95,000 = 124,667

F = 4 × 0.8125 × 0.375 × 95,000 + 1 × 0.8125 × 0.3125 × 95,000 = 139,902

G = 4 × 0.8125 × 0.375 × 95,000 + 1 × 44,000 × 0.5185 = 138,595

117,304(B) = 0.875 = efficiency of joint. 134,062(A) .......

Click to view image

A-6 Example: butt- and double-strap joint, quadruple-riveted.

A = strength of solid plate = P × t × TS.

B = strength of plate between rivet holes in the outer row = (P - d) t × TS.

C = shearing strength of eight rivets in double shear, plus the shearing strength of three rivets in single shear = N × S × a + n × s × a.

D = strength of plate between rivet holes in the second row, plus the shearing strength of one rivet in single shear in the outer row = (P - 2d) t × TS + 1 × s × a.

E = strength of plate between rivet holes in the third row, plus the shearing strength of two rivets in the second row in single shear and one rivet in single shear in the outer row = (P - 4d) × TS + a × s × a.

F = strength of plate between rivet holes in the second row, plus the crushing strength of buttstrap in front of one rivet in the outer row = (P - 2d) t × TS + a × b × c.

G = strength of plate between rivet holes in the third row, plus the crushing strength of buttstrap in front of two rivets in the second row and one rivet in the outer row = (P - 4d) t × TS + n × d × b × c.

H = crushing strength of plate in front of eight rivets, plus the crushing strength of buttstrap in front of three rivets = N × d × t × c + n × d × b × c.

I = crushing strength of plate in front of eight rivets, plus the shearing strength of two rivets in the second row and one rivet in the outer row, in single shear = N × d × t × c + n × s × a.

Divide B, C, D, E, F, G, H, or I (whichever is the least) by A, and the quotient will be the efficiency of a butt- and double-strap joint, quadruple-riveted, as shown in Figure A-5.

TS = 55,000 psi

t = 1/2 in. = 0.5 in.

b = 7/16 in. = 0.4375 in.

P = 15 in.

d = 15/16 in. = 0.9375 in.

a = 0.6903 sq. in.

s = 44,000 psi

S = 88,000 psi

c = 95,000 psi

Number of rivets in single shear in a unit length of joint = 3. Number of rivets in double shear in a unit length of joint = 8. .......

A = 15 × 0.5 × 55,000 = 412,500

B = (15 - 0.9375) 0.5 × 55,000 = 386,718

C = 8 × 88,000 × 0.6903 + 3 × 44,000 × 0.6903 = 577,090

D = (15 - 2 × 0.9375) 0.5 × 55,000 + 1 × 44,000 × 0.6903 = 391,310

E = (15 - 4 × 9.0375) 0.5 × 55,000 + 3 × 44,000 × 0.6903 = 400,494

F = (15 - 2 × 0.9375) 0.5 × 55,000 + 0.9375 × 0.4375 × 95,000 = 399,902

G = (15 - 4 × 0.9375) 0.5 × 55,000 + 3 × 0.9375 × 0.4375 × 95,000 = 426,269

H = 8 × 0.9375 × 0.5 × 95,000 + 3 × 0.9375 × 0.4375 × 95,000 = 473,145

I = 8 × 0.9375 × 0.5 × 95,000 + 3 × 44,000 × 0.6903 = 447,369

386,718(B) = 0.937 = efficiency of joint. 412,500(A) .......

Click to view image

A-7 Figures A-6 and A-7 illustrate other joints that may be used in which eccentric stresses are avoided. The butt- and double-strap joint with straps of equal width shown in Figure A-6 may be so designated that it will have an efficiency of from 82 to 84 per cent and the saw-tooth joint shown in Figure A-7 so that it will have an efficiency of from 92 to 94 per cent.

Click to view image

SECTION 2

BRACED AND STAYED SURFACES

A-8 (a) The allowable loads based on the net cross-sectional areas of staybolts with V threads are computed from the following formulas. The use of Whitworth threads with other pitches is permissible.

(1) The formula for the diameter of a staybolt at the bottom of a V thread is:

D - (P × 1.732) = d.

where D = diameter of staybolt over the threads, inches, P = pitch of threads, inches, = 1/number of threads per inch, d = diameter of staybolt at bottom of threads, inches, 1.732 = a constant. .......

(2) When U. S. threads are used, the formula becomes:

D - (P × 1.732 × 0.75) = d.

(b) Tables A-1 and A-2 give the allowable loads on net cross-sectional areas for staybolts with V threads having 12 and 10 threads per inch.

Click to view image

Click to view image

Click to view image

A-10 Table A-4 gives the net areas of segments of heads for use in computing stays.

TABLE A-4

Net Areas of Segments of Heads Where d, as Given in Sections 14-11.107 (subd. [a]) and 14-11.108, Is Equal to Three Inches

SECTION 3

METHOD OF CHECKING SAFETY-VALVE CAPACITY BY MEASURING MAXIMUM AMOUNT OF FUEL THAT CAN BE BURNED

A-12 The maximum quantity of fuel C that can be burned per hour at the time of maximum forcing is determined by a test. The maximum number of heat units per hour, or CH, is then determined, using the values of H given in paragraph A-17. The weight of steam generated per hour is found by the formula:

W = C × H × 0.75 1100 .......

where W = weight of steam generated per hour, pounds, C = total weight or volume of fuel burned per hour at time of maximum forcing, pounds or cubic feet, .......

H = heat of combustion of fuel, Btu per pound or per cubic foot (see par. A-17).

The sum of the safety-valve capacities marked on the valves shall be equal to or greater than W.

A-13 Example 1. A boiler at the time of maximum forcing uses 2,150 pounds of Illinois coal per hour of 12,100 Btu per pound. Boiler pressure is 225 psi gage.

C × H = 2150 × 12,100 = 26,015,000

W = C × H × 0.75 ÷ 1100 = 17,740

A-14 Example 2. Wood shavings of heat of combustion of 6,400 Btu per pound are burned under a boiler at the maximum rate of 2,000 pounds per hour. Boiler pressure is 100 psi gage.

C × H = 2000 × 6400 = 12,800,000

W = C × H × 0.75 + 1100 = 8730

A-15 Example 3. An oil-fired boiler at maximum forcing uses 1,000 pounds of crude oil (Texas) per hour. Boiler pressure is 275 psi gage.

C × H = 1000 × 18,500 = 18,500,000

W = C × H × 0.75 + 1100 = 12,620

A-16 Example 4. A boiler fired with natural gas consumes 3,000 cubic feet per hour. The working pressure is 150 psi gage.

C × H = 3000 × 960 = 2,880,000

W = C × H × 0.75 + 1100 = 1960

A-17 For the purpose of checking the safety-valve capacity as described in paragraph A-12, the following values of heats of combustion of various fuels may be used:

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

Click to view image

SECTION 4

AUTOMATIC WATER GAGES

A-18 Automatic shutoff valves on water gages, if permitted to be used, shall conform to the following requirements:

(a) Check valves in upper and lower fittings shall be of solid noncorrosive metal ball type to avoid need for guides.

(b) Ball check valves in upper and lower fittings must open by gravity and the lower ball check valve must rise vertically to its seat.

(c) The check balls must not be smaller than one-half inch diameter, and the diameter of the circle of contact with the seat must not be greater than two thirds of the diameter of the check ball. The space around each ball must be not less than one-eighth inch, and the travel movement from the normal resting place to the seat must be not less than one-quarter inch.

(d) The ball seat in the upper fitting must be a fiat seat with either a square or hexagonal opening, or otherwise arranged so that the steam passage can never be completely closed by this valve.

(e) The shutoff valve in the upper fitting must have a projection which holds the ball at least one-quarter inch away from its seat when the shutoff valve is closed.

(f) The balls must be accessible for inspection. Means must be provided for removal and inspection of the lower ball check valve while the boiler is under steam pressure.

These restrictions do not apply to closing the valves by external methods.

TABLE A-11

Minimum Metal Thickness of Bodies of Cast-Iron Malleable-Iron and Bronze Screwed Fittings (The following table is taken from ASA B16d-1941, B16c-1939, MSS SP-11-1944, B16-15-1947 and MSS SP-31-1931.)

All pressures are in pounds per square inch (gage).

SECTION 5

FUSIBLE PLUGS

A-19 (a) Fire-actuated fusible plugs, if used, except as provided in paragraph A-20(i), shall be filled with tin of the following composition, having a melting point between 445 and 450 degrees Fahrenheit.

(b) The fusible metal shall extend from the water end of the plug to the point of least diameter of the hole and shall be carefully alloyed to the casing. A test shall be made to determine that the fusible metal is not loose in the plug.

(c) Fusible plugs shall be renewed at least once each year. Casings which have been used shall not be refilled.

(d) Fusible plugs filled with tin as specified in (a) shall not be used for pressures and temperatures which will cause the plug to fail while it is submerged in the boiler water.

TABLE A-12

Numbers for Ring-Joint Gaskets and Grooves

All dimensions given in inches.

The edge of each flange and the outside circumference of each ring shall carry corresponding identification marks, i.e., R11, R45, etc.

*When ordering rings for nominal pipe sizes which may have either oval or octagonal shaped rings, purchasers must specify oval or octagonal shaped rings as desired.

(e) The fusible metal may be partly replaced by a bronze plug loosely fitted to the hole and of such size that it will pass freely through the hole on the fire side, from which side it must be inserted into the casing. Such plug shall be properly alloyed to the casing with the same fusible metal as required by (a).

A-20 (a) Waterside plugs are fusible plugs which are inserted from the water side of the plate, flue, or tube to which they are attached. Fireside plugs are fusible plugs inserted from the fire side of the plate, flue, or tube to which they are attached.

(b) The casing of the fusible plugs shall be made of composition conforming to specification SB-61.

(c) Typical designs of fusible plugs are given in Figure A-10.

Click to view image

(d) The bore of the casing shall be tapered continuously from the water end of the casing for a distance of at least one inch to a diameter of not less than three-eighths inch at a point not less than one-half inch from the fire end. The diameter of the bore at either end shall be not less than one-half inch. The hole on the fire end shall be as large as possible and may be of any shape provided the cross-sectional area at all points is greater than the area of the least cross section of the fusible metal.

(e) A fusible plug shall be of such length that when installed it shall project at least three-quarters inch on the water side of the plate, tube, or flue. It shall extend through the plate, tube, or flue on the fire side as little as possible but not more than one inch.

(f) A fireside plug may be designed so as to be inserted by means of a plug-type wrench, so as to reduce the projection on the fire side.

(g) If a fire-actuated fusible plug is inserted in a tube, the tube wall shall be not less than 0.22 inch thick, or sufficient to give four full threads.

(h) Fusible plugs which comply with the requirements of paragraphs A-19 and A-20 must be stamped on the casing with the name of the manufacturer, and on the water end of the fusible metal, "ASME Std." Fusible plugs which comply with the rules and regulations of the U. S. Bureau of Marine Inspection and Navigation (now under the U. S. Coast Guard) will be considered to comply with the requirements of paragraphs A-19 and A-20 and may have the letters "ASME" stamped on the casing instead of on the fusible metal.

(i) Fusible metal, other than tin as specified in paragraph A-19(a), for use under temperatures exceeding 450 degrees Fahrenheit, may be used and the casing may be made of other material and shape than specified in paragraph A-20(b), (c), and (d) if the metal and the casing are approved by the administrative authority. Such plugs shall not be marked as "ASME Std."

A-21 Fire-actuated fusible plugs, if used, shall be located at the lowest permissible water level for different types of boilers as given below; steam-actuated plugs, if used, shall be so located that they will operate when the water level is at the point where a fire-actuated fusible plug would be located if installed under these rules.

(a) Horizontal-return tubular boilers -in the rear head, not less than one inch above the upper rows of tubes, the measurement to be taken from the line of upper surface of tubes to the center of the plug, and projecting through the sheet not less than one inch. When the distance between the uppermost line of tubes and the top of the steam space is 13 inches or less, the fusible plug may be at a lesser distance than one inch above the upper row of tubes, but in no case shall the bottom of the plug be located below the level of the top of the uppermost row of tubes.

(b) Horizontal flue boilers -in the rear head, on a line with the highest part of the boiler exposed to the products of combustion, and projecting through the sheet not less than one inch.

(c) Traction, portable, or stationary boilers of the locomotive type or boilers having water-tube elements and crown sheets -in the highest part of the crown sheet, and projecting through the sheet not less than one inch.

(d) Vertical fire-tube boilers (standard type) -in an outside tube, not less than one third the length of the tube above the lower tube sheet.

(e) Vertical fire-tube boilers (submerged-tube type) -in the upper tube sheet and projecting through the sheet not less than one inch.

(f) Water-tube boilers with straight tubes, box, or sectional headers and longitudinal or cross-horizontal drums -in the water and steam drum not less than six inches above the bottom of the drum, over the first pass of the products of combustion, and projecting through the sheet not less than one inch.

(g) Water-tube boilers of the bent-tube type -in the front water and steam drum, not less than six inches above the bottom of the drum, exposed to the products of combustion, and projecting through the sheet not less than one inch.

(h) Vertical water-tube boilers -in the shell of the top drum and not less than six inches above the upper tube sheet, and projecting through the sheet not less than one inch; so located as to be at the front of the boiler and exposed to the first pass of the products of combustion.

(i) Scotch marine-type boilers -in the combustion chamber top, and projecting through the sheet not less than one inch.

(j) Dry-back Scotch-type boilers -in the rear head, not less than two inches above the upper row of tubes, and projecting through the sheet not less than one inch. When the distance between the uppermost line of tubes and the top of the steam space is 13 inches or less, the bottom of the fusible plug may come at a lesser distance than two inches above the upper row of tubes; but in no case shall the plug be located below the level of the top of the uppermost row of tubes.

(k) Fire-tube boilers of the refractory-lined firebox type -in the rear head not less than two inches above the upper row of tubes. When the distance between the uppermost row of tubes and the top of the steam space is 13 inches or less, the bottom of the fusible plug may come at a lesser distance than two inches above the upper row of tubes but in no case shall the plug be located below the level of the top of the uppermost row of tubes.

(l) Fire-engine boilers are not usually supplied with fusible plugs. Unless special provision is made to keep the water above the firebox crown sheet other than by natural level, the lowest permissible water level shall be at least three inches above the top of the firebox crown sheet.

(m) For other types and new designs, fusible plugs shall be placed at the lowest permissible water level, subject to the direct radiant heat of the fire or in the direct path of the products of combustion, as near the primary combustion chamber as possible.

SECTION 6

STANDARD PRACTICE FOR MAKING HYDROSTATIC TESTS ON A BOILER PRESSURE PART

A-22 Scope. This method of test is applicable only to materials having a definite proportional or elastic limit such as most carbon and alloy steels. It is not applicable to materials with indefinite or indeterminate proportional limits such as cast iron and most nonferrous materials. *The principle upon which the test is based assumes that the most highly stressed point in the pressure part will be subjected to a permanent set when the stress at this location reaches the proportional or elastic limit of the material. Since the stress will be directly proportional to the hydrostatic pressure, the determination of the pressure which stresses the weakest point to the proportional limit will permit a calculation of the maximum allowable working pressure that will result in a safe working stress in accordance with requirements of Part 14 for the material from which the part is made at the maximum operating temperature.

A-23 Material. The structure shall be made from material approved for its intended use by the New York State Boiler Code [Part 14].

A-24 Workmanship. The dimensions and minimum thickness of the structure to be tested should not vary materially from those actually used. If possible, the structure to be tested should be selected at random from a quantity of such intended for use.

A-25 Preparation for test. (a) It is necessary to test only the weakest point of the structure but several points should be checked to make certain that the weakest one is included. The less definite the location of the weakest point, the more points should be checked.

(b) The movement of the reference points may be measured with reference to a fixed surface, or two reference points may be located on opposite sides of a symmetrical structure and the total deformation between those two points measured.

(c) Indicating micrometer gages accurate to 0.001 inch are most suitable for measuring deformation of the structure at the reference points although any form of accurate micrometer may be used.

(d) A hand test pump is satisfactory as a source of hydrostatic pressure. Either a test gage or a reliable gage which has been calibrated with a test gage should be attached to the structure.

(e) The maximum hydrostatic pressure that must be provided for will vary from two to three times the expected maximum allowable working pressure for carbon-steel structures.

(f) The location of the weakest point of the structure may be determined by applying a thin coating of plaster of Paris or similar material, and noting where the surface coating starts to break off under hydrostatic test. The coating should be allowed to dry before the test is started.

A-26 Hydrostatic test. (a) The first application of hydrostatic pressure need not be less than the expected maximum allowable working pressure. At least 10 separate applications of pressure, in approximately equal increments, should be made between the initial test pressure and the final test pressure.

(b) When each increment of pressure has been applied the valve between the pump and the structure should be closed and the pressure gage watched to see that the pressure is maintained and no leakage occurs. The total deformation at the reference points should be measured and recorded and the hydrostatic pressure recorded. The pressure should then be released and each point checked for any permanent deformation which should be recorded.

(c) Only one application of each increment of pressure is necessary.

(d) The pressure should be increased by substantially uniform increments, and readings taken until the elastic limit of the structure has obviously been exceeded.

(e) The pressure part shall not have been subjected to a pressure greater than the designed maximum allowable working pressure prior to making the proof hydrostatic test.

A-27 Physical characteristics of metal. Determine the proportional limit of the material in accordance with A.S.T.M. specification E8-42, standard method of tension testing of metallic materials. It is important that this be determined from a number of specimens cut from the part tested, after the test is completed, in order to insure that the average proportional limit of the material in the part tested is used to calculate the safe working pressure. The specimens should be cut from a location where the stress during the test has not exceeded the proportional limit, so that the specimens will be representative of the material as tested. These specimens should not be cut with a gas torch as there is danger of changing the proportional limit of the material.

A-28 Plotting curves. A single cross-section sheet should be used for each reference point of the structure. A scale of one inch equals 0.01 inch deformation, and a scale of at least one inch equals the approximate test pressure increments has been found satisfactory. Plot two curves for each reference point, one showing total deformation under pressure and one showing permanent deformation when the pressure is removed.

A-29 Determining proportional limit of pressure part. (a) Locate the proportional limit on each curve of total deformation as the point at which the total deformation ceases to be proportional directly to the hydrostatic pressure. Draw a straight line that will pass through the average of the points that lie approximately in a straight line. The proportional limit will occur at the value of hydrostatic pressure where the average curve through the points deviates from this straight line.

(b) In pressure parts such as headers, where a series of similar weak points occur, the average hydrostatic pressure corresponding to the proportional limits of the similar points may be used

(c) The proportional limit obtained from the curve of total deformation may be checked from the curve of permanent deformation by locating the point where the permanent deformation begins to increase regularly with further increases in pressure. Permanent deformations of a low order that occur prior to the point really corresponding to the proportional limit of the structure, resulting from the equalization of stresses and irregularities in the material, may be disregarded.

(d) It should be made certain that the curves show the deformation of the structure and not slip or displacement of reference surfaces, gages, or the structure.

A-30 Determining maximum allowable working pressure. (a) Having determined the proportional limit of the weakest point of the structure, the corresponding maximum allowable working pressure may be determined by the formula:

P = H S.. E .......

where P = maximum allowable working pressure, pounds per square inch,

H = hydrostatic pressure at the proportional limit of the pressure part, pounds per square inch,

S = working stress permitted by Tables P-5, P-6, or P-7 for the material at the maximum operating temperature as determined by requirements of Part 14,

E = average proportional limit of material, pounds per square inch.

(b) For carbon-steel material, complying with a specification of Part 14 and with a minimum tensile strength not over 62,000 psi, the proportional limit may be assumed to be two fifths of the average tensile strength of the specified range. Where no range is specified, the average tensile strength may be assumed as 5000 psi greater than the minimum. This will eliminate the necessity for cutting tensile specimens and determining the actual proportional limit. Under such conditions, the material in the pressure part tested should have had no appreciable cold working or other treatment that would tend to raise the proportional limit above the normal value. The pressure part should preferably be normalized after forging or forming.

A-31 Retests. A retest should be allowed on an additional structure if errors or irregularities are obvious in the results.

A-32 Testing parts made from material without definite proportional limit. (a) Pressure parts made from cast iron or nonferrous materials without a well-defined proportional limit must be tested until failure occurs by rupture. The hydrostatic pressure at which rupture occurs must be determined. If excessive leakage occurs at rolled joints or at gasketed handhole fittings, they may be seal-welded for the test to permit test to destruction, provided the welding does not materially increase the strength of the part. No deflection measurements will be necessary. The average actual tensile strength of the material from which the part tested is made must be determined from test specimens cut from the part tested. If this is not practicable, the tensile strength must be assumed to be the maximum of the range given in the specifications for the material.

(b) The maximum allowable working pressure may be determined by the formula:

P = H S.. E .......

where P equals; maximum allowable working pressure, pounds per square inch,

H = hydrostatic pressure at time of rupture, pounds per square inch,

S = working stress permitted by Tables P-5, P-6, or P-7 for the material at the maximum operating temperature as determined by requirements of Part 14,

E = average actual tensile strength from test specimens, or maximum of the range in specification, pounds per square inch.

(c) It is possible that certain designs of pressure parts may result in concentrated stresses at critical points which may be relieved by yielding of the material at these points prior to rupture, so that failure may occur at some other point and not indicate the point of maximum stress at pressures below that causing rupture. There may be conditions which would make a test to destruction impracticable. Under such conditions a special test may be made from a carbon steel material of the same dimensions and thickness as used for the material in question. This special test part can then be tested in accordance with paragraphs A-23 to A-32. The maximum allowable working pressure for the part made from the material in question would be determined by using the proper value of S for the material in the formula in paragraph A-30. The value of E used in the formula would be that for the carbon steel material from which the special test part is made.

Note: Paragraphs A-33 to A-64 inclusive are incorporated in sections 14-12.1 to 14-12.29, inclusive.

SECTION 7

EXAMPLES OF METHODS OF COMPUTATION OF OPENINGS IN SHELLS

Note: Applications of the rules in section 14-11.170 are given in the following examples.

A-65 A boiler shell for 275 psi working pressure has an inside diameter of 36 inches and is made of one-half inch thick plate having a minimum ultimate tensile strength of 55,000 psi. Is it permissible to use a two-inch pipe connection by tapping a hole for the pipe directly into the shell?

K = PD = 275 × 37 = 0.925 or 92.5 per cent 2St 2 × 11,000 × 0.50 .......

Dt = 37 × 0.5 = 18.5

From the chart in Figure P-34, the maximum allowable diameter of an unreinforced opening is d = 3.05 inches.

The two-inch tapped hole has a diameter of 2.375 inches and according to Table P-12 requires at least 0.435 inches thickness for threads. Also, although the working pressure is above 100 psi, the size of the threaded connection is not greater than the maximum of three-inch pipe size permitted when this pressure is exceeded. Therefore the connection meets the requirements of Part 14.

A-66 A special forging (such as shown in Figure A-11[a]) for a three and one-half inch pipe connection is inserted in a boiler shell the working pressure of which is 100 psi. The length of thread is two inches, the outside diameter of the portion projecting through the shell is four and three-quarters inches, and the cross-sectional area of the forging is 2.25 square inches. This construction complies with the rule that a threaded connection over three-inch pipe size shall be used only for working pressures of 100 psi and under. The length of thread is sufficient, as indicated by Table P-12.

Click to view image

(a) Seal welded. If seal welding only is applied to the forging, the opening is classed as an unreinforced hole having in this case a diameter of four and three-quarters inches. The rules in subdivision (a) of section 14-11.170 govern in this case. Assume the following data: inside diameter of shell = 48 inches; thickness = 1/2 inch; working pressure 100 psi; material is grade A of specification SA-285 (45,000 psi minimum ultimate tensile strength).

K = PD = 100 × 49 = 0.545 or 54.5 per cent 2St 2 × 9000 × 0.50 .......

Dt = 49 × 0.50 = 24.5

From Figure P-34, d = 6.15 inches. The actual diameter is four and three-quarters inches, and therefore this construction meets the requirements of Part 14.

(b) Strength welded. If the outside diameter of the neck of the forging (in this case four and three-quarters inches) is greater than d as given by the charts in Figure P-34, the welds must be strong enough to develop a minimum required amount of strength (strength welding). The rules in subdivisions (e) to (h) of section 14-11.170 govern in this case. Assume: inside diameter, thickness, working pressure, and material of shell same as in (a); working temperature = 850 F; S = 5700 psi (see Table P-7).

K = 100 × 49 = 0.86 or 86 per cent ... 2 × 5700 × 0.50 .......

Dt = 49 × 0.50 = 24.5

From Figure P-35, d = 4.12 inches. As the outside diameter of the neck of the forging (or hole in the shell) is four and three-quarters inches, the forging must be strength welded to the shell and the design must comply with subdivisions (e) to (h) of section 14-11.170.

(1) Assume a fillet weld on the outside with 15/16 inch legs. The weld dimensions then comply with detail 3 of Figure P-36. Since the forging is rigidly welded to the shell, the diameter of the opening is now four inches and the limits therefore are as shown in Figure A-11(a).

Cross section through shell = 0.50 × (8 - 4.75) = 1.62 sq in. Cross section through forging = (1 15/16 × 0.70) + (1.50 × 0.5) = 2.20 sq in. Cross section through weld = 2 × 1/2 × 0.9375 × 0.9375 = 0.88 sq in. .......

Total actual cross section. 4.70 sq in. .......

The required thickness when E = 0.90 (see § 14-11.61) is

t = PR = 100 × 24 = 0.468 inches... SE 5700 × 0.90 .......

Required cross section = area (EFGH + JKLM ) = 0.468 × (8 2) = 2.810 square inches.

Therefore paragraph (1) of subdivision (g) of section 14-11.170 has been complied with.

(2) The fillet weld can fail in tension, around the circumference of the four and three-quarters inches diameter, or it can fail in shear around the circumference of the mean diameter of 511/16 inches. The strength of that part of the weld on one side of the center line (on a semicircle) must be at least equal to that specified in paragraph (2) of subdivision (g) of section 14-11.170, and in subdivision (h) of section 14-11.170. The allowable working stress of the weld in shear is 0.8 times the allowable working stress in tension.

Strength of weld in tension = 0.9375 × 1/2 × (3.14 × 4.75) × (0.9 × 5700) = 35,900 pounds.

Strength of weld in shear = 0.9375 × 1/2 × (3.14 × 5.6875) × (0.8 × 0.9 × 5700) = 34,300 pounds.

The weld is weaker in shear.

Strength of forging = 2.25 × 5700 = 12,800 pounds.

Strength of cross section represented by (QFGR + JSTM ) = 0.468 × (4 - 2) × 5700 = 5330 pounds.

Therefore paragraph (2) of subdivision (g), and subdivision (h) of section 14-11.170 have been complied with.

A-67 A studded connection such as shown in Figure A-11(b) is for six-inch: 400-pound American Standard seamless pipe. The data for the shell are as follows: inside diameter = 60 inches; thickness = 2 1/8 inches; working pressure = 325 psi; working temperature below 650 F; material grade B of specification SA-285. The fiat for the raised face reduces the shell thickness to 1 9/16 inches, at the edge of the opening.

K = 325 × 64.25 = 0.670 or 67 per cent.. 2 × 10,000 × 1.5625 .......

Dt = 64.25 × 1.5625 = 100.4

From Figure P-34, d = 8 inches. The actual equivalent diameter is the diameter of the hole in the shell plus the diameters of two stud holes, or 6.049 + (2 × 0.875) = 7.799 inches. Therefore the connection meets the requirements of Part 14. This example is for a shell built to stresses permitted by Figure P-7. For fusion-welded or seamless construction where design stresses exceed those given in Table P-7 as permitted under subdivision (c) of section 14-11.61, subdivision (l) of section 14-11.85 and subdivision (a) of section 14-11.90, this example will have a different value of S and K but the procedure of calculation will be similar.

A-68 (a) A four-inch extra heavy pipe is welded into a shell as shown in Figure A-11(c). The shell has an inside diameter of 30 inches, a thickness of three-eighths inch, and a working pressure of 200 psi. The material is in accordance with specification SA-285. The weld, as shown in Figure A-11(c), complies with detail 4 of Figure P-36.

Cross section I = 0.375 (7.652 - 4.50) = 1.181 sq in. .......

Cross section II = 0.337 × 1.217 × 2 = 0.820 sq in. .......

Cross section III = 2 × 1/2 × 0.50 × 0.50 = 0.250 sq in .......

Total actual cross section = 2.251 sq in.

The required thickness when E = 0.90 is

t = 200 × 15 = 0.303 inch. 11,000 × 0.90 .......

Required cross section = 0.303 × (7.652 - 2) = 1.71 square inches.

Therefore paragraph (1) of subdivision (g) of section 14-11.170 has been complied with.

(b) The weld can fail in tension by tearing around its circumference on a diameter of five and one-half inches. Since welding equivalent to that required under the rules in section 14-11.40 to 14-11.49 has been used, the allowable stress in tension is 11,000 × 0.90 or 9900 psi (see § 14-11.41).

Strength of weld in tension = 0.375 × 1/2 × 3.14 × 5.50 × 9900 = 32,100 pounds.

The attachment of the nozzle can also fail by shearing through the weld and the nozzle neck (along the line NP in Figure A-11[c]), around the circumference of the mean diameter of (5.50 + 3.826) × 1/2 = 4.663 inches. The allowable working stress of the weld in shear is 0.8 times the allowable working stress in tension.

Strength of attachment in shear = (0.50 + 0.37) × 1/2 × 3.14 × 4.663 × (0.8 × 9900) = 48,600 pounds.

From the above, the construction is weaker in tension than in shear.

Strength of nozzle = (Area II) × S = 0.820 × 11,000 = 9020 pounds.

Strength of cross section represented by (QFGR + JSTM ) = 0.303 × (3.826 - 2) × 11,000 = 6090 pounds.

Therefore paragraph (2) of subdivision (g) of section 14-11.170 has been complied with.

Strength of attachment in shear = (0.50 + 0.337) × 1/2 × 3.14 × 4.663 × (0.8 × 7000) = 34,400 pounds.

From the above, the construction is weaker in tension than in shear.

A-69 (a) A 16-inch welded circular nozzle-type manhole is located on a seamless shell (grade 1, specification SA-266), as shown in Figure A-11(d). The shell data are as follows: inside diameter = 96 inches; thickness = 2 inches; working pressure = 500 psi; working temperature = 600 F. Welding suitable for power boilers is used.

(1) The welds at the manhole neck comply with detail 1 and the welds on the reinforced pad with details 5 and 6 of Figure P-36.

Cross section I = 2 × (32 - 18) = 28.00 sq in. .......

Cross section II = 1.00 × 5.25 × 2 = 10.50 sq in. .......

Cross section III = 2.5 × (32 - 21.5) = 26.25 sq in. .......

Cross section IV = two 3/4 -in. fillets + one 1-in. fillet = 2.12 sq in. .......

Total actual cross section = 66.87 sq in.

The required thickness when E = 0.90 is

t = 500 × 48 = 2.222 inches. 12,000 × 0.90 .......

Required cross section = 2.222 × (32 - 2) = 66.66 square inches.

Therefore the design meets the requirements of paragraph (1) of subdivision (g) of section 14-11.170.

(2) Welding of the manhole neck:

Strength of welds in tension = (2 × 0.75) × 1/2 × 3.14 × 18 × (0.9 × 12,000) = 458,000 pounds.

Strength of welds in shear = (2 × 0.75) × 1/2 × 3.14 × 18.75 × (0.8 × 0.9 × 12,000) = 381,000 pounds.

The welds at the manhole neck are weaker in shear.

Strength of neck = (Area II) × S = 10.50 × 12,000 = 126,000 pounds.

Strength of cross section represented by (QFGR + JSTM ) = 2.222 × (16 2) × 12,000 = 373,000 pounds.

Therefore the welding of the neck meets the requirements of paragraph (2) of subdivision (g) of section 14-11.170.

(3) Welding of the reinforcing pad:

Strength of welds in tension = [(1.00 × 1/2 × 3.14 × 21.5) + (0.625 × 1/2 × 3.14 × 36)] × (0.9 × 12,000) = 746,000 pounds.

Strength of welds in shear = [(1.00 × 1/2 × 3.14 × 20.5) + (0.625 × 1/2 × 3.14 × 36.635)] × (0.8 × 0.9 × 12,000) = 589,000 pounds.

The welds at the reinforcing pad are weaker in shear.

Strength of reinforcing pad = 2.5 × (32 21.5) × 12,000 = 315,000 pounds.

Strength of cross section represented by (QFGR + JSTM ) = 373,000 pounds, as above.

Therefore the welding of the reinforcing pad meets the requirements of paragraph (2) of subdivision (g) of section 14-11.170.

The above design corresponds to type H shown in Figure P-36. For other types of construction employing reinforcing pads, such as types F, G, J, and others, the methods of calculation are similar to the above.

(b) This example is for a shell built to stresses permitted by Figure P-7. For fusion-welded or seamless construction where design stresses exceed those given in Table P-7 as permitted under subdivision (c) of section 14-11.61, subdivision (l) of section 14-11.85 and subdivision (a) of section 14-11.90, this example will have a different value of S and K but the procedure of calculation will be similar.

A-70 An eight-inch riveted nozzle is located on a drum as shown in Figure A-11(e). The shell data are as follows: inside diameter = 54 inches; thickness = 1 1/4 inches; working pressure = 350 psi; working temperature = 440 F; minimum tensile strength = 55,000 psi.

Assume the nozzle to be 8 inches inside diameter, the thickness of the nozzle neck to be 9/16 inch, the thickness of the riveting flange to be 3/4 inch, and the outside diameter of the riveting flange to be 17 1/4 inches.

Assume also 18 1 1/4-inch rivets on a 14-inch rivet circle with one 9/32-inch rivet holes straddling the longitudinal center line through the nozzle; minimum tensile strength = 55,000 psi. The opening in the shell is 83/4 inches to provide space for calking.

The weakest section will be along a line parallel to the longitudinal axis passing through the centers of the two rivets nearest the center line of the nozzle as shown in Figure A-11(e).

The neck of the nozzle may be considered as reinforcement for a distance of two and one-half times its thickness measured from the back of the riveting flange. Therefore the distance of line AB (see Figure A-11[e]) from the outside of the shell equals1; (2.5 × 0.5625) + 0.75 = 2.16 inches.

Cross section I = 17.5 - (8.41 + 1.282 + 1.282) × 1.25 = 8.16 sq. in. .......

Cross section II = (2.16 × 2 × 0.59) + [17.07 - (7.62 + 0.59 + 0.59 + 1.282 + 1.282)] × 0.75 = 2.55 + 4.28 = 6.83 sq in.

Total actual cross section = 14.99 sq in.

The required thickness when E = 0.90 is

t = 350 × 27 = 0.955 inches.. 11,000 × 0.90 .......

Required cross section = 0.955 × (17.5 2) = 14.81 square inches.

Therefore the design meets the requirements of paragraph (1) of subdivision (g) of section 14-11.170.

Failure can occur by shearing of the rivets on one side of section AA. The ultimate strength of the rivets in shear is 44,000 psi.

Area of rivets to one side of section = 0.7854 × 1.282 × 1.282 × 7 = 9.05 square inches.

Ultimate strength of rivets in shear = 9.05 × 44,000 = 398,000 pounds.

Ultimate strength of nozzle = (Area II)× X U.T.S. = 6.83 × 55,000 = 376,000 pounds.

Ultimate strength of cross section represented by (QFGR + JSTM) = 0.955 × (8.41-2) × 55,000 = 336,000 pounds.

Therefore the riveting meets the requirements of paragraph (2) of subdivision (g) of section 14-11.170.

Failure can also occur by the internal pressure blowing the nozzle off the shell.

The ultimate strength of the rivets in tension is 55,000 psi.

Total area of rivets = 0.7854 × 1.282 × 1.282 × 18 = 23.3 square inches.

Ultimate strength of rivets in tension = 23.3 × 55,000 = 1,282,000 pounds.

Required strength due to internal pressure acting on 8 3/4-inch calking circle with factor of safety of 5 = 0.7854 × 8.75 × 8.75 × 350 × 5 = 105,400 pounds.

If the riveting flange is calked also on the outside, then the required strength due to internal pressure acting on 17 1/4-inch calking circle, with factor of safety of 5 = 0.7854 × 17.25 × 17.25 × 350 × 5 = 410,000 pounds.

Therefore the riveting meets the requirements of paragraphs (1) and (2) of subdivision (j) of section 14-11.170.

The shell plate may fail by tearing around through the rivet holes. Checking by applying the rules in subdivision (b) of section 14-11.76:

Click to view image

Therefore the design meets the requirements of subdivision (b) of section 14-11.76.

This example is for a shell built to stresses permitted by Figure P-7. For fusion-welded or seamless construction where design stresses exceed those given in Table P-7 as permitted under subdivision (c) of section 14-11.61, P-185(l)* and subdivision (a) of section 14-11.90, this example will have a different value of 8 and K but the procedure of calculation will be similar.

Click to view image

Click to view image

SECTION 9

APPROVAL OF NEW MATERIALS UNDER THE BOILER CONSTRUCTION CODE

A-75 If possible, the material should be identified with an A.S.T.M. specification or tentative specification. If the material varies only slightly from an A.S.T.M. specification by the addition, say, of a small amount of alloying element, it should be stated that the material will comply with some specification except as noted and the exception should be stated not only as to chemical composition, but as to physical properties and test results.

A-76 If no A.S.T.M. specification can be applied, the following information should be given in the same form as used by the A.S.T.M.:

(a) Chemical composition, including for ferrous materials, carbon, manganese, phosphorus, sulphur, and silicon, together with alloying elements, if any.

(b) Tensile properties, over the temperature range of contemplated service. Where the vessels are to be stress-relieved or heat-treated, the tensile tests shall be made after the specimens are similarly treated.

(c) Creep strength over any temperature range of contemplated service within which the phenomena of creep will lower the working strength of the material.

In both (a) and (b) the range rather than an exact determination of the properties should be given within which it is commercially practicable to reproduce the material.

A-77 If any heat treatment is required to produce the tensile properties, it should be stated.

A-78 The Brinell or Rockwell hardness should be given unless the information is well known for the material in question. This information is particularly advantageous if the hardness is higher than for the particular materials specified for boiler pressure parts.

A-79 If the material is to be used at low temperatures, below 0 Fahrenheit, the impact strength at these low temperatures should be given.

A-80 It is very important to know whether a new material is subject to critical conditions at temperatures within the range of use or fabrication. By critical conditions is meant a material change in brittleness, hardness, ductility, grain size, etc.

A-81 It should also be stated if the material is subject to age hardening or critical structural changes by a combination of physical and temperature conditions, such, for example, as the age hardening of certain aluminum alloys after cold working and subsequent heat treatment. This is particularly important in conditions which might occur during fabrication that result in this critical condition.

A-82 Unless the material is well known and not unusual in its characteristics, the coefficient of thermal expansion over the range of temperature within which the material will be used should be given, particularly if there is any marked variation from that of ordinary carbon steel.

A-83 It should be stated whether the material is commercially available and can be purchased within the specified range of chemical and physical qualities. If the material is covered by patents so that it cannot be manufactured by anyone who wishes to use it without securing a license or paying royalties, it should be so stated.

A-84 If the material is to be welded it should be stated whether any special procedure is required for electric fusion or gas welding and the amount of experience available for determining the weldability. It should be stated whether the material is subject to air hardening during welding. If special procedure must be followed in fusion welding the material, or if the vessel is stress-relieved or heat-treated after welding, the method should be specified, including the proper temperatures. As a check on weldability, it is recommended that the tests described in Subpart 14-15 be made, unless equivalent information is available.

A-85 Tests, results of which are submitted to the Board of Standards and Appeals, should be made upon the thickest plates contemplated, except as otherwise dictated by A.S.T.M. standards.

SECTION 10

MAXIMUM ALLOWABLE WORKING PRESSURES-THICK SHELLS

A-125 Shells for internal pressure. When the thickness of the shell exceeds one half of the inside radius, the maximum allowable working pressure on the cylindrical shell of a boiler or drum shall be determined by the following formulas:

Click to view image

Footnotes

* For method of testing parts made from such materials, see paragraph A-32.

* So in original. Reference probably should be to present subdivision (l) of section 14-11.85.

Explanatory of Subparts 14-11 and 14-12 and containing matter which is not mandatory unless specially referred to in the sections therein.